Collecting and classifying mill



Sept. 17, 1940. c. H. KIDWELL 2,214,905

COLLECTING AND CLASSIFYING MILL Filed Dec. 23. 1937 2 Sheets-Shet 1 I LINYENTOR (700 flamldKidWell,

; m /wr p -17.1940. I C(H. KIDWELL 2,214,905

COLLECTING AND CLASSIFYING KILL Filed Dec. 23, 1937 2 Sheets-Sheet 2 alz y INVENTOR.

6700 bhmldfidwell,

ATTURNEYBF Patented Sept. 17, 1940 PATENT OFFICE oonmc'rmc ANDCLASSIFYING MILL Cleoliarold Kidwell, Short Hills N. J. V ApplicationDecember 23, 1937,, Serial No. 181,259

60mins.

This, invention relatesto an apparatus for separating. and classifyingthe particles ofa finely divided material according to their respectivesizes.

' More specifically it comprehends the separation and classification ofmaterials which have been reduced to a finely divided state by grindingor a similar process of attrition, and which are suspended in a fluidmedium forease of transmission and grinding during the process.

An attrition process of v...th'e above character is disclosed in mycopendingapplication Serial No. 86,426,- applied for Jointly withNicholas N. K. Stephanoff, joint inventor with me of theinventionpresented therein. In .the above-mentioned process the materialto be reduced is fed into one end of a curved tubular device through theagency of a high velocity stream of fluid, preferably a gas. Thevelocity of the entering 20 fluid is so chosen that the velocity of thecombined'fiuid andmaterial is at all times less than,

or at most equal to the critical velocity, so that a stream line flow ofthe material and the fluid' curved portions of the tubular device athigh velocity gives rise to a centrifugal force which together with theeffect of skin friction on the walls of the classifier causes the massof material and fluid in the central portion of the tube to be forcedtoward the outer wall thereof. This gives rise to the phenomenon termeddouble inverse flow" in the above identified copending 35 application,in which the fluid isgiven'two rotationalmovements such that in anycross sectional plane through .curved sections oi" the tubular device,half the fluid rotates in a clockwise direction, whereas the other halfrotates in a counterclockwise direction. In the central portion. of theplane through the tube, the fiow of both halvesis the same and is in thedirection of the centrifugal force causing themotion. llhis peculiarmotion of the fluid medium causes the particles of the material. to rubvigorously against one another so that they are reduced to a veryfinestate of division during the process of attrition.

The double inverse" flow of the fluid medium is utilized in thisinvention to provide for the separation and classification of the finelydivided material which isdischarged from a classifier of the characterbriefly described above.

An object of the invention, accordingly, is to provide a novel means forthe rapid and effective separation and classification of finely dividedmaterials according to relative particle sizes.

1 A further object of the invention is to provide an apparatus of theabove character in which the finely divided material is suspended in afluid 5 medium and the separation and classification is accomplished bythe combined action of centrifugal force and by double inverse flow ofthe medium in which the particles are suspended- Another object of theinvention is to provide 10 an apparatus of the above character in whichthe classification is aided by the effect of the force of gravity on theparticles of finely divided material.

In accordance with the present invention, the finely divided material,suspended in a fluid medium, is fed to a curved tubular classifier whichis provided with an axial slot in its periphery. The heavier and largerparticles in suspension, due to the double inverse motion of the fluidaided by the centrifugal force acting, are discharged through the axialslot, while the finer material continues through the classifier. In thismanner, the larger particles may be separated from the finer ones, orparticles ofvarying degrees of fineness may be separated and collectedas indicated below.

Additional objects will be apparent from the following detaileddescription and from the accompanying drawings in which:

Fig. 1 is a view in front elevation of a helical classifier constructedin accordance with this invention.

Y Fig. 2 is a top view of a modified classifier constructed inaccordance with the invention, in which the device is formed withseveral concentric tubular portions.

Fig. 3 is a view in section illustrating'a further modification of theclassifier, for obtaining several degrees of fineness. 40

Fig. 4 is a view 1 section illustrating a modification in whichcollecting chamber is substituted for the helical collecting chamberdisclosed in Fig. 1;

Fig. 5 is a view in partial section illustrating an adaptation of theconstruction of Fig. 4 in which two separate devices are used to obtainclassification and collection.

Fig. 6 is ,a view in partial section illustrating an "adaptation of ,theconstruction of Fig. 1 in which a pair of helices of varying radii areused to obtain separation and collection.

Referring to Fig. l a collector is shown formed by ahelical coil It towhich is secured a second collector coil il in such fashion thatthe twoare .55

tion with the double inverse fiow 'of the fluid outlined above, and morefully described in my above identified copending application, causes thecoarser particles in suspension to move toward the do outer wall of thecoil It whence they are discharged through the slot l2 into thecollector coil I I. The angle of the helix generated by each coll shouldbe-greater than the angle of repose for I the material collected so thatthe latter will; so readily slide along vthe surface of the collectorcoil Ii from which it will bedischargedthrough the outlet It. The finerparticles in suspension will remain in the coil II and will continuedownwardly until they are discharged alongwith the a. fluid medium fromthe outlet II. It is obvious -thatbyv ry1 8thelengthofthecollectorcoilsthe amount ofmaterial separated from the fluid 4 medium can becontrolled within reasonably ,close limits. and if desired all thematerial may IQ ,diflbhltlfll from the outlet ll leaving the to palethrough the outlet ii. If detb'eoutletu maybe provided withavalvo tml'lthwhich the material maybevalvedoff as .2! inl'igdamodifiedformofthecollectingapparatus isshown which isformed of thetwo concentric coils it and II respectively. the outer surface of coilit being tangentially in contact with the inner surface of coil l'l. Asin Fig. l,

a narrow continuous slot is formed at the point of tangency of the twocells, which communicates therebetween. The finely divided material influid suspension enters through the inlet U- passage "from which itpasses to the coil It.

' Ash travels through passage II. due to the combined eifects ofcentrifugal iorce and double inverse flow, the coarser material movestoward the outer surface of the coil I! and is eventually discharged,into the coil ll through the slot formed between the two cells. Spacedin the bottom of'coil I'I are a number of apertures through which thecollected coarser material may pass into a suitable container. The fluidmedium continues on, and is discharged through the outlet 20 asclearfluid or containing a small amount of very finely divided material insuspension depending upon the rate of flow through the collecting deviceand the length thereof.

As illustrated in Fig. 3 the collecting classifier shown in Fig. 2 maybe provided with three coils several varying degrees of flnenessin thecol- "lected product or more complete collection.v As before, the fluidbearing material enters at the q inlet 24 from which it is fed into thecoil 2|. Due

double inverse flow of the fluid medium, the coarser and heavierparticles are thrown against the outward portion of the coil in thedirection 10 of the arrow, through a communicating slot 25 iormedbetween cells 2| and 22. In this modiflcation, double inverse fluid flowis also maintained in the second coil 22, so that with this constructionalso, the relatively coarser par- ;5 ticles are thrown against its outersurface in the 2|, 22 and 22' respectively in orderrto obtain to theJoint action of centrif force and the direction indicated by the mow.-,Theytheh pass into the hopper-shaped coil 22, through a slot 28 formedbetween coils 22 and 23. Since any fluid fiowin this latter coil will besuchas not to prevent the collection of the particles I. therefrom, thecoarse and relatively heavy material drops upon the inclined surfaces210! the hopper shaped coil 23, and is discharged through the opening 28in the bottom thereof. The particles which have collected in coil 22fall downl0 wardly and are discharged through spaced openings 2| formedin the inner surface of thiscoil. With this construction, therefore, itis possible to collect the finely divided -material in three'rliflerentstages of classification, which may be controlled asmentioned above by varying the \fiuid velocity through the coils andalso by changing their respective lengths.

length of the coil, and through which the relatively coarse materialisdischarged as described above. About the cylindrical member 32 acylindrical collecting chamber 34 is formed'and is provided with a coverplate 25 and a base plate I! in which the discharge openings 31 areformed. 1

.The discharge openings. 31 are provided with caps "which may beintermittently withdrawn to remove the material which has collected inthe chamber It. The fluid medium in which the finely divided materialwas ori inally suspended. if fed in through the end 80, is discharged 7through the outlet it which forms the lower extreinity of thehelical'coil 3|. In this modification also, the relative amount offinely divided material discharged with the fluid medium can 0 becontrolled by varying the length of the helical coil 2|, and also-tosome extent. by varying the v velocity of the fluid medium therein.

The collecting device of this invention is illustrated in afurther'modiflcation in Fig. 5 which 5 is adapted to permit theseparation and classification of vthe finely divided and suspendedmaterial into two or more classes. It comprises the two collectingchambers 40, in each of which two helical coils 4| and 42 are mounted asshown. 60

It. Here they fall downwardly by gravity upon 0 the funnel shapedsurfaces 46 of the collecting chamber 40, whence they are dischargedthrough the passage 46 to a suitable container. Any number ofsimilarclassiflers may be connected in series in order to obtain as manygrades of classi- 65 fication as may be desired, and it is possible inthis manner to remove substantially all of the finely divided materialwhich was originally suspended in the fluid medium.

In the embodiment shown in Fig. 6, the col- 7o lector comprises ahelical coil 41 to which a collector coil 48 is tangentially secured,and between which a continuous communicating slot 49 is formed. It willbe noted as each helix rises its radius decreases, so that thecentrifugal force 16 decrease as they pass downwardly the classifien Inthis case the part of. the material is thrown out through the slot ll inthe upper portion 'of,the apparatus where the centriiugal force isgreatest, remainingpore tion being removed as it progresses downwardlythroug'hthe'classifler, so that all of the material V Q. to thedischarge opening l2.

1 It is evident that in any of the modiflcations may be removed andclear fluid may be discharged from the lower opening IO.

The material-bearing fluid may also enter the device through the lowerextremity II, in which casetheheavierparticleswillberemovedinthe lowerpart ,of the device where'the centrifugal force is least,' while thelighter material particles will be removed in the upper section'where,

due to the decreased radius,,.the centrifugal force is relativelygreater. The clear fluid will then be'discharged from the upperextremity ll while the separated and collected material will bedischarged through the lower extremity II of the collector tube ll. Inthis modification also, the

helix angle is chosen to be greater than the angle of repose for thematerial collected,"so that the latter will readily slide down thecollector tube shown the helical tube which constitutes the main elementof the classifier may be constructed to decrease in diameter along itslength .or in- I crease in diameter depending on the-results desired.For example, in the modiflcatlonshown in Hg. 3, the second coil 2! maybe made of slightly less diameter than coil II to increase the eifect ofthe double inverse flow of the fluid me- 7 diumin coil 22, a featurewhich must be conin view of the fact that the heaviest particles havebeen removed. Similarly if it is.

deairedto gradualy reduce the eflect of the double inverse flow, thecoil "may be made of larger diameterthanthecoillltosecurethedesiredrasult.

This invention provides a whereby flnely divided materials may berapidly and eflec tively as may be required, and as pointed out above,it

classiiilsdv into as many different particle sires is possible to removesubstantially all of the ma- .terial from the fluid medium so thattheprocess l. A device for separating and classifying flnely' dividedmaterial suspended in a fluidmedium,

comprising a coiled, tubular member of substantially circular crosssection adapted under proper flow velocities to cause the fluid to newin a plurality of paths, means to supply materialladen ,iiuid to thesaid tubular member, a second coileq'tubular member of substantiallycircular cross section concentric with the-flrst member terial to asecond tubular abouts common center of curvature, and tangent to theouter wall of the periphery of said first member for receiving theseparated material,

and a communicating slot between the two said members formed in thetangential portion 'to cooperate with the said fluid flow for removing aportion of flnely divided material from the said fluid medium and fordirecting the removed material to, the saidsecond tubular member.

2. Adevice for separating and classifying flnely divided materialsuspended in a fluid medium,

bers of substantially circular cross section con-' centricallydisposedabout a common axis 'and respectively tangent to one another, at leastone of which is adapted to cause the fluid to flow in a plurality ofpaths, means to supply materialbearing fluid to one of the said tubularmembers,

.and longitudinally extending communicating slots between the saidtubular members, in the comprising a plurality of helical,..tubularmem-- I tangential portions. thereof, 'to cooperate with' the said fluidflow for removing a portion of flnely divided material from the saidfluid medium, and for directin the said removed maember.

3. A device for separating and classifying flnely divided materialsuspended in a fluid medium,

comprising a plurality of helical, tubular members concentricallydisposed about a common 'axis, and respectively tangent to one anotherat their peripheries, at least one of which is adapted to cause thefluid to flow in a plurality of streamline paths, means to supplymaterial-bearing fluid .to one of the said tubular members,communicating slots between the said tubular members in the tangentialportions thereof, to cooperate with the said fluid flow for removing aportion of flnely divided material from the said fluid medium, and fordirecting it to a second tubular member, the helix angle of the saidtubular members being greater than the angle of repose for the finelydivided material todacilltate its discharge from the device.

4. A device for separating and classifying flnely divided materialsuspended in a fluid medium comprising an elongated, tubular member '0!substantially'circular cross section having a helical portion adaptedtocause the fluid to flow in a plurality of paths including adjacentportions which are parallel and unidirectional in a direction away fromthe center of curvature of the member, means to supply material-ladenfluid to .the said tubular member, a continuous axial slot formed in theperiphery of and substantially co-extensive in length with said helicalportion of the said tubular member to cooperate with the said fluidflow,- for removing a portion of flnely divided material from the saidfluid medium, and a chamber about the said tubular member for collectingthe material so removed. 5. A device for separating and classifyingflnely divided material, suspended in a fluid medium, comprising aplurality of curved, elongated tubular members, concentrically disposedabout a common axis and respectively tangent to one another so that oneis outwardly positioned with respect to a plurality of other inwardlydisposed members, the said inner tubular members being adapted to causethe fluid to flow in a plurality of paths, means to supply the materialbearing fluid to the innermost of the said inner tubular 'members,communicating slots between the tubular members in the adjacenttangential portions thereof to cooperate with the said fluid flow,whereby the heavier material is directed through the said "slotsintq thetubular member disposed; terial in e fluid mediump 'comprising a;tcoiled' j." outwardiythereof, said outermost-inner tubular tubularmember of substantially; circular-cross member being 'formedfwith anaperture tl'irough secti6n having a; narrow slot extendinz' albngq whichmaterial may be removed therefrom-"fori its length in its outera,periphery,"{: the saidw 5 collection; '-communicating" slots between"the 'mel'nber beingfldaptedto causef the fluidto' flow-'5 outermostinnertubular member and'the'afore in aplurality of paths inclu'clingportio'x'is;which 1 mentioned outwardly 'pbsitioned tubular member 5are-parallel and unidirectionalin 'ai'direetion to-" in the tangentialportions thereof cooperatinrf-ward the 'said "sl0t,'.=means toSuppIYFmateri'al -Q with thefluid flow whereby'theheavier material*laden fiuid t0 the member, and-'collector mea.nsm. is direted throughthe s'ldt in jthe'secon'qinner 'extendin'gs'ubstentially thelength 'ofthe -mem-fq tubular member into the "outer tubular member; f berand overthe slotrto receive finely; divided. 1' and" means to remove and"collect material from -materielj1romtheflnid"medium; the 'said Outertubularmember; j I I v 6. A .devic'eior separating finely divided ma.-CIEO'IHAROID f

